IBM owes much of its recent success to the business it does outside of the United States, but even while Americans tighten their belts, the company is continuing to prove remarkably successful in its home market.

International Business Machines reported a 26 percent increase in quarterly profit Wednesday from a year earlier, easily surpassing Wall Street’s estimates. Earnings were helped by the decline of the dollar; Most of IBM’s business is outside of the United States, so a falling dollar lifts reported income.

But the company also gained because of 6 percent rise in U.S. sales, an improvement over the last quarter of 2007, when revenue rose only 2 percent.

Mark Loughridge, the company’s chief financial officer, said during an interview that IBM’s resilience in challenging times was the result of its strategy, which was fine-tuned early last year. He described it as “two separate views of the global market.”

In developed countries, including the United States, where customers were likely to be cutting back, IBM tailored its services and software offerings to help customers cut costs, conserve cash and improve productivity. Those kinds of technology investments, Loughridge said, made sense when the economy was weak.

In fast-growing markets like China, India and Eastern Europe, Loughridge said, IBM had invested heavily to capture business, and had positioned itself as a leading supplier of hardware, software and services to banks, government agencies and telecommunications companies. In India, for example, IBM is a major supplier to the three largest telecommunications companies in the country, who together are signing up 55,000 cell phone customers every day.

“In these emerging markets, it’s all about technology infrastructure for us,” Loughridge said.

IBM, the largest technology services company in the world, reported first-quarter profit of $2.32 billion, compared with $1.84 billion a year ago. Its earnings per share were $1.65, well ahead of…

Tags: business, Communications, Hardware, Software, Technology